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Jo_EL · Nov 30, 2011, 12:10 PM

I have an oil hot water system, the hot water running through the house has low pressure. Where do I find the heater coil to see if it needs to be cleaned or replaced

massplumber2008 · Dec 1, 2011, 06:14 AM

Hi Jo_EL

The tankless coil is immersed inside the boiler itself... only way to check it is to isolate it and then run a weak acid solution through it to try to breakdown the mineral deposits that may have built up and is clogging things up. This is usually best left to a plumber/oil burner technician... ;)

With that being said, the first thing to check in cases like this is going to be the shutoffs at the cold water INLET and at the hot water OUTLET (if there are any shutoffs on the outlet at all) of the tankless coil. Here, if there is a boiler drain at the tankless coil you can open that full open and see what the pressure/volume looks like. If you have significant pressure then, most likely, the issue is after the coil (at another shutoff), or it could be that the coil is clogged on the outlet side only... that kind of stuff.

Anyway, the only way to find out what is going on is to break this down into manageable steps. Check the easy stuff, and then check the harder stuff like cutting shutoffs out and replacing with new shutoffs, and then finally, when all avenues have been exhausted, you try an acid wash on the coil (tricky, like I said) and see if that fixes all.

If all else fails you either get a replacement tankless coil or you opt. in for a water heater or a strorage tank and be done with this!

Back to you...

Mark

Jo_EL · Dec 1, 2011, 07:05 AM

I was surprised when the tech. came out to clean the oil burner, I watched him vacuum it and replace the nozzle and the oil filter, I asked him about lousy hot water pressure, he blamed it on build up in the pipes and turned my water temp up to 180 degrees... never mentioned the coil. I remembered after he left that I did have an acid wash done about 3 yrs. Ago. Can it be done again? Or is that too much acid on the coil.

massplumber2008 · Dec 1, 2011, 11:25 AM

You could see if someone will acid wash the coil again... really have nothing to lose because if an acid wash does the coil in, the coil was shot anyway... ;)

In terms of the 180 degree temp. increase, I don't like that UNLESS you have a mixing valve (see image) at the outlet of the tankless coil? Let me know on that, OK?

Mark